==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail pro 4.4 (MySQL) 
- Deployed with iRedMail Easy or the downloadable installer? no
- Linux/BSD distribution name and version:  debian
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  mysql
- Web server (Apache or Nginx): nginx
- Manage mail accounts with iRedAdmin-Pro? yes and via shell
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

hi

I configured split domain with the mx record pointing to o365
https://gist.github.com/iredmail/fda90a … c18638e047

in settings.py and iptables firewall i added ips to allow incoming emails on port 25 (without authentication) only via o365 ips. Entire server communicates on port 25 only with o365 ips.

for a domain abc.com

in vmail/domain table COLUMN split_transport i put entry
smtp:abc-com.mail.protection.outlook.com:25

split domain mail communications in works correctly both ways between o365 and our server

however I am facing issues with MLMMJ mailing list

example below

mailing list created on our server : saleslist@abc.com
user@abc.com (moderator) sends email to saleslist@abc.com

we get bounced error message from 0365 as follows

#############
Original Message Details
Created Date: 25/06/2026 5:17:16 am
Sender Address: user@abc.com
Recipient Address: saleslist-moderators@abc.com
Subject: RE: Please moderate saleslist@abc.com: Bookings Open
Error Details
Error: 553 5.7.1 <user@abc.com>: Sender address rejected: not logged in
Message rejected by: ns1.aaa.com
############

it seems that the mail is getting routed to o365 and then routed back by 0365 server to our server instead of getting processed / delivered locally to the mailing list locally.

how do I resolve this?

thanks